// removing white space
$fileName = isset($_FILES["file"]["name"]) ? preg_replace('/\\s+/', '-', $_FILES["file"]["name"]) : '';
// removing special character but keep . character because . seprate to extantion of file
$fileName = preg_replace('/[^A-Za-z0-9.\\-]/', '', $fileName);
// rename file using time
$fileName = !empty($fileName) ? time().'-'.$fileName : '';
$attachments = array();
if (!empty($fileName)) {
$arr = wp_upload_bits($fileName, null, file_get_contents($_FILES["file"]["tmp_name"]));
$url = !empty($arr['url']) ? $arr['url'] : 'не прикреплен';
$attachments = array($arr['file']);
}
wp_mail($to, 'Форма заказа расчета кухни', $message, $header, $attachments);
wp_die();